Compensating radial work support for an internal centerless grinder



June 17, 1958 OVELY 2,838,886

' J. W. L COMPENSATING RADIAL WORK SUPPORT FOR AN INTERNAL CENTERLESSGRINDER Filed June 5, 1957 2 Sheets-Sheet 2 INVENTOR Me John WLOve@ /40-L jfiwhn AO/6 Maw {26 k ATTORNEY6 United States Patent COMPENSATINGRADIAL WORK SUPPORT FOR AN INTERNAL CENTERLESS GRINDER John W. Lovely,Springfield, Vt., assignor to Bryant Chucking Grinder Company,Springfield, Vt., a corporation of Vermont Application has, 1957, SerialN0. 663,685 6 Claims. (0]. 51-103 This invention relates to improvementsin internal grinding machines of the type wherein an annular workpieceisradially supported on a preformed outside surface for rotation infrictional relationship to supporting shoes peripherally spaced alongthe surface, and a tool is apas raceway rings for anti-frictionbearings, must be produced at a fast rate while holding narrow tolerancelimits in concentricity and diametrical dimensions. Because ofprevailing economic and technological reasons the pre- 7 formed outsidesurfaces are allowed to have dimensional variations between successiveworkpieces and the internal grinder is expected to accept suchworkpieces at random and produce a hole therein concentric with thepreformed, radially supported perimeter. Although this condition ofadded complication could be wholly or at least partially remedied bypregaging and classification grouping of workpieces, any such means haveheretofore proven to be uneconornical. From the foregoing, it followsthat in order to accomplish the above-stated results the centers ofsuccessive workpieces always must be located at the predefined positionirrespective of random diametrical variations between the consecutiveworkpieces.

In the co-pending application of Roald Cann, filed April- 1, 1957,Serial No. 649,765, there is disclosed a device which includesself-containing sensing means for automatically adjusting the relativelyposition of the radial supporting shoes to compensate for differences ofoutside diameters between successive workpieces. This invention relatesto certain additional improvements which would make the Canncompensating radial'work support more versatile.

It is therefore an object and purpose of this invention to provide animproved apparatus for accepting at random workpieces having differentoutside diameters and supporting them for internal centerless grindingso that the centers of the different outside diameter workpieces arelocated on a single definite line normal to the line of relative feedmotion between the work and the tool.

For a complete understanding of this invention, reference may be had tothe following detailed description taken in connection with theaccompanping drawings, wherein:

Figure 1 is a side elevation with a portion in section, illustrating apreferred embodiment;

'Figure 2 is a side elevation illustrating a variation of the embodimentof Figure l;

[Figure 3 is a sectional view taken along line 33 of Figure 2. I

Referring to Figure 1, 10 indicates-the surface of a grinding machinebed whereon a bracket 12 is supported, forming part of a headstockassembly which includes a rotatable work-driving spindle. A driver face18 on the headstock spindle normal to its axis supports the workpieceaxially in frictional relationship and drives the workpiece in a manneras described in the Arms et a1. patent, 2,63 5,395, referred to above.

A rotatable spindle 20 carries a tool T and is shown as located withinthe inner periphery of an annular work- .piece W. The machine isarranged for transverse feed movement between the workpiece and the toolalong a line of feed F running from the center of spindle 20 to a center0 of a workpiece of median outer diameter when radially supported withthe center in a predetermined position ona line normal to the feed lineby means which will be described forthwith. The tool is adapted to bepresented to the inner surface of the annular workpiece for the purposeof generating an accurate inner diameter. A member 22 consists of afixed portion 21 rigidly attached to a face plane of the bracket 12 byscrews 25, and a movable portion 23. A shoe 16 is nested in the fixedportion 21 and another shoe 24 is nested in movable portion 23 angularlyspaced from shoe 16. The movable portion 23 containing shoe 24 is hingedto portion 21 by a weakened portion 28. This hinge permits a limiteddegree of rocking movement about its pivotal axis only. Flexible reeds,or other types of hinges could, of course, be utilized instead of theweakened portion hinge 28. With this hinge arrangement, movable portion23, which contains the shoe 24, may pivot about the pivotal axis ofhinge 28'. This pivotal axis or pivot point is located on an imaginaryline P which is parallel with an imaginary line N normal to the line offeed through the center of the workpieces. The distance A from the pivotpoint to line F along line P is half the distance 2A between lines N andP. Also located on line P is the fulcrum of a bar 40, which is indicatedas a knife-edge bearing 42.

On the line N diametrically opposite the shoe 16 is another shoe 26which is a sensing element. This shoe 26 is nested in one end of anadder bar 40 which is arranged with a fulcrum at a knife edge bearing 42located on line P a distance 2A from line N. The adder bar 40 carries anadjustable button 44 on the end opposite shoe 26 and equidistant fromthe fulcrum, that is, both button 44 and shoe 16 are a distance 2A fromline P on opposite sides thereof. The adjustable button 44 is adaptedtocooperate with an anvil 46 on the rockable member 23.

A fluid-power cylinder 50 is attached to the bracket 12 and may besupplied with pressurized fluid through a conduit 52 from a suitablesource, not shown. A piston 54 is contained within the cylinder and,when pressurized fluid is supplied to the cylinder behind the piston itis displaced until seated against a shoulder 55 in the bottom of thecylinder. A piston rod 56 terminating in a knife edge cooperates withthe bearing 42 to form the fulcrum of the bar 40 along line P. When thefluid pressure is removed, a pair of springs 58-58 will displace the bar40 away from the position established by the shoulder 55.

A compression spring 34 is interposed between a lug 32 on bracket 12 andmovable support portion 23 to urge this'portion to pivotcounter-clockwise about pivot point or hinge 28 and thereby bias shoe 24against the outer periphery of the workpiece W. To adjustably andselectively limit the amount of rocking movement, a pin 35 is attachedto member 23 and the outer portion of this pin is threaded at 36 toaccommodate nuts 38 which may be adjusted to determine the extent of therocking movement. V

A locking arrangement is provided for a rockable member 23. This deviceconsists of a carrier 60 rigidly attached to bracket 12 by means ofscrews 61 and hav- Pa te ntd June 17, 1958 ing a locking device 62 forthe purpose of locking member 23 in its adjusted position against theface plane of bracket 12.

Initially, the compensatingv radial work support is preferably adjustedin the following manner: A workpiece of median outside diameter isseated against shoes 16 and 24 and piston 54 is forced by the fiuidpressure to the position shown, seated against shoulder 55, therebyplacing the sensing element 26 in contact with the outer periphery ofthe workpiece W. Stop 44 is then adjusted in contact with anvil 46 untilan imaginary line connecting the points of contact between stop 44 andanvil 46 and the shoe 26 and the workpiece is substantially normal toline Pand parallel to line F. The adjusting nuts 38 are adjusted tolimit the rocking movement of portion 23 so that with no workpiecepresent, shoe 24 will be positioned a minute amount closer to centerthan the radius of the smallest diameter workpiece permissible.

In operation, if a workpiece larger than the'median outside diameter isintroduced, the sensing element 26 will be displaced away from shoe 16an amount equal to the additional diameter, thus rocking the arm 40about pivot 42 and moving stop 44 in an opposite direction and therebycausing portion 23 to translate same amount at the point of contact onanvil 46. Due to the particular location of the pivot point 23, theamount of translation at the point of contact between shoe 24 and theworkpiece is halved, corresponding to the additional radius size. Inother words, sensing element 26 diametrically opposite from fixed shoe16 senses the outside diameter of the workpiece and translates thisdiameter into a radius adjustment of shoe 24. If a workpiece of smallerdiameter than the median size is introduced, the changes would occur inan opposite sense. From the foregoing, it may be seen that, withinreasonable limits, any sized workpiece when placed in the compensatingwork support will always be positioned with the center of its supportedoutside diameter on the line N.

When the workpiece has been positioned in the support and the shoe 24has been automatically located to compensate for the outer diameter ofthe workpiece, the locking means 62 are operated to fix the position ofshoe 24-. Then the fluid pressure may be relieved in conduit 52,permitting springs 58 to lift the bar 40, thereby removing sensingelement 26 from contact with the workpiece. The machine is then incondition to commence the grinding operation.

Figure 2 illustrates a modification of the invention. In thismodification, the sensing element is diametrically opposite the movablesupport shoe instead of being diametrically opposite the fixed supportshoe. This requires a different arrangement of the geometry of the partsinvolved to position a movable shoe in accordance with the differentoutside diameters of successive workpieces. A bracket 112, which isfixed to the bed of the grinding machine, supports a member 122 whichhas a portion 121 fixed to the bracket by means of screws 12:7. A fixedradial support shoe 116 is nested in the fixed support portion 121 tosupport a workpiece of median outside diameter with its center on theline of feed F with the line N normal thereto at the point of the fixedsupport. A movable portion 123 of memher 122 is hinged to portion 121 bya suitable hinge such as weakened portion 123 in a manner similar tothat described in connection with Figure 1. A shoe 124 is fixedly nestedin movable portion 123 to support a workpiece of median size outsidediameter where line F intersects a line between this point of supportand the hinge or pivot point at 128, which latter line is preferablyparallel to line N. Portion 123 also carries an 'anvil 146 located on aline P parallel to the line F. This anvil and the pivot point 128 arethe same distance, 2A, from line F on opposite sides thereof. A carrierwhich is rigidly secured to the bracket 112 by screws 161 carries alocking device 162 for accomplishing a locking function in a similarmanner to that described in conjunction with Figure l.

A cambered pin 156 is fixedly secured to bracket 112 at a positionlocated on line P which is parallel to line F a distance A therefrom. Asensing element 126 is attached to a bar 140 which is secured toacarrier 170. The carrier is pivotally supported at 172 on a lug 174integral with bracket 112 and may be swingably positioned as indicatedin broken lines if it is desired to have radial workpiece loading. Aforkshaped portion of the carrier 170 is provided with a generally V-formed bearing means 171 which pivotally support journal portions of asemicircular pin 142 attached to the bar 140, and this pin has a planethrough the center thereof in contact with pin 156 to form the fulcrumfor the bar 140. A sensing element 126 carried by one end of the arm adistance A from the fulcrum contacts the outer periphery of a mediansize workpiece on line F diametrically opposite shoe 124. The arm 140carries a contact button 144 on the end opposite sensing element 126equidistant from the fulcrum, and this button 144 is adapted to contactthe anvil 146. 7

Due to the location of the various contact points, fulcrums, pivot pointand sensing element, the kinematics of the mechanism and the describedsystem will give the same results as that described in connection withFigure 1. That is, when the distances from the fulcrum of arm 140 toshoe 126 and button 144 are equal and the distance between the line Fand the pivot point 128 is twice this distance, the sensing element 126will sense the outside diameter of the workpiece and translate thischange in outside diameter into a movement of shoe 124, which movementwill be one-half of the change in outside diameter.

For the purposes of illustration only, applicant has disclosed twoembodiments of an improved compensating radial work support for aninternal centerless grinding machine. These illustrated embodiments arenot limiting as the invention is limited only by the scope of theappended claims.

I claim:

1. In an internal grinding machine, having a rotatable work driver, atool adapted to be positioned in working relationship to the interior ofan annular workpiece on which an internal surface .is to be generatedconcentric with a performed external surface, means to impart a relativetransverse movement between the axes of said tool and work driver alonga line of feed; a radial work support comprising: first and second shoesradially supporting a workpiece on said performed external surface andin frictional relationhip thereto, the first shoe being a single-linesupport and supporting the workpiece on a line parallel to said line offeed and being rigidly mounted in relation to the work driver, thesecond shoe supporting the workpiece with a wall of the workpieceinterposed in the space between the shoe and the tool in the path ofsaid transverse movement, a movable member carrying the second shoe; aseparate third shoe used as a sensing element contacting the preformedexternal surface of the workpiece when in grinding position, said thirdshoe located opposite one of said other two shoes to sense the diameterof the workpiece; and a separate movable member carrying said third shoeand cooperating with said movable member carrying the second shoe toposition said second shoe carrying member to compensate for randomdifferences between the outer diameter of successive workpieces. I

2. A device as defined in claim 1 and further compris- 'ing lockingmeans to lock said member in its compensated adjusted position andwherein said movable member is rockableabout a pivot.

3. A device as defined in claim 2 wherein spring means are provided toconsistently urge said rockable member in a direction to displace 5: idsecond shoe toward the position of said tool whilst in workingrelationship; and means to adjustably limit the amount of displacement.

4. A device as defined in claim 3 wherein said sensing element isdiametrically opposite said first shoe on a line normal to said line offeed; and further comprising: a bar pivotally supported on a linerunning through said pivot point of said rockable member and normal tosaid line of feed, said bar carrying said sensing element and beingprovided with an adjustable stop element adapted to cooperate with aportion of said rockable member, said stop element and said portionlocated on the side of the normal line on which said pivots are locatedopposite the 15 2,646,652

sensing element and equidistant therefrom.

5. A device as defined in claim 4- further comprising means todefinitely locate the fulcrum of the bar at a predetermined point on thenormal line through the fulcrum, and means consistently urging the baraway from said line of feed.

6. A device as defined in claim 3 wherein said third shoe used as asensing element is located opposite said second shoe and wherein saidthird shoe movable carrying member is pivotally mounted on anotherhinged support for moving said third shoe sensing element into and outof diameter sensing position.

References Cited in the file of this patent UNITED STATES PATENTS BloodJuly 28, 1953 2,758,427 Quimby Aug. 14, 1956

